A collection of jumbled bones unveiled September 5 once belonged to a dolphinlike creature that lived some 170 million years ago. It’s called the Storr Lochs Monster, and it’s one of the few good skeletons scientists have from the Middle Jurassic, which spanned from about 174 to 164 million years ago.

“That’s what sets this fossil apart,” says paleontologist Stephen Brusatte of the University of Edinburgh in Scotland. “It’s very, very rare, it has lots of bones and it comes from this really dark interval of time.”

Brusatte and colleagues know that the fossil belonged to an ichthyosaur, a type of ancient marine reptile, and that it probably reached 3 to 4 meters in length, about the size of a small rowboat. But until they study it in more detail, researchers can’t say much else. “It’s probably a new species,” Brusatte says, “because there’s hardly anything else known from this time period.”

An amateur fossil hunter discovered the skeleton 50 years ago on the Isle of Skye, embedded in limestone harder than concrete. The limestone had been baked solid by volcanic activity about 100 million years after the sea creature lived, Brusatte says. It can take pneumatic drills, diamond-tipped saws and months of work to extract bones from this type of rock, he says. When the fossil was discovered, not many — if any — people could do this sort of fossil extraction.